Include b-significant

[aronsho]

seismostats.b_significant

1D
autocorrelation
function that cuts ordered magnitude series (equal n_m, random n_m)

2D
autocorrelation (Morans I)
function that cuts magnitudes (random and hexagon for now?)
necessary for example, but maybe can be done later:

• transforming data from lon-lat into x-y
• cut out box and project onto plain

Both
Function that estimates significance threshold for given n
function to visualize the b-value
Function to visualize n vs MAC, including significance threshold
Notebook that shows example how to use (b-value estimation)